Hello and welcome to R2R first of all!
You will enjoy it here...
As for your question... if it has a brown mat/stolen then it is Briarium, which is a type of Gorgonian.
Pachyclavularia, or Green Star Polyps tend to have a flatter, rubbery appearance to its stolen. They stolen is also a purple to reddish color.
Good luck and happy reefing...